Save it, don't blow it on a fancy car or electronic toys. I wouldn't go throwing it around in the market either unless you know what you are doing or have someone who does. Park it for a bit in something that will get a secure, decent return and don't make any fast decisions otherwise Poof! It could be gone sooner than you think. This will allow time to think through all options and the best use for the cash. At 18 it could pay for college, save for a down payment towards a house in a few years, etc
It's a nice chunk of change but certainly not life changing and I wouldn't think it would require substantial management.